It is known with electric tooth brushes to provide a time switch, which, starting from switching-on of the electric tooth brush, emits a discernible signal after a predetermined time duration for a user. The signals serve to indicate to the user the end of the cleaning time. The user is made aware of the end of the optimal cleaning time through the use of acoustic or optical signals. From WO 96/14025, it is known to not emit an acoustic or optical timer signal, rather instead to switch the drive motor of the tooth brush on and off rapidly so that the drive motor stutters. This can be done while the device is either in the hand or in the mouth of the user.
In addition, it can be provided that the electric tooth brush is switched off after termination of the target cleaning time automatically. This is inexpedient if the timer-signal merely indicates that a partial region of the teeth, such as, for example, a biting quadrant, has been completely cleaned. In WO 97/19650, it therefore proposed to switch again to regular cleaning operation after the stuttered operation, so that the biting quadrant can be cleaned completely according to the desire of the user. As soon as the user changes to another biting quadrant, he can start anew the timing member by means of a button, in order again to be provided the target cleaning time for this new biting quadrant. This method for indicating the target cleaning time does not fulfill the wishes of all tooth brush users, however.
From DE 197 28 964 A1, a tooth brush with a device is known, which signals to the tooth brush user the beginning and end of the optimal tooth cleaning time. On the tooth brush, a knob or slide switch is mounted, with which at the beginning of the teeth cleaning, an acoustic signal can be released, which is repeated automatically after approximately three minutes. In addition, a signal after approximately three months of using the tooth brush can be emitted, whereby the user is informed that the tooth brush should be replaced with a new tooth brush.
U.S. Pat. No. 6,029,303 discloses a manual tooth brush with an electric circuit, which emits a discernible signal regarding the cleaning time. The beginning of the cleaning time can be determined, for example, by means of a movement sensor, which releases a timing member, whereby, at the end of the time, a signal discernible by the user is emitted from the timing member of an electrical circuit. Also, the possibility exists that with the electronic circuit, the entire cleaning time is added up and a further signal from the electronic circuit is then emitted, which falls below the recommended use time of the tooth brush.